New rules for leading spaces of binary operators

[so298]

Hi, @dalance!

I added some new rules for leading spaces of binary operators.
The names of the new rules are the following:

• style_operator_arithmetic_leading_space
• style_operator_boolean_leading_space
• style_operator_integer_leading_space

Each of these rules corresponds to the following existing rules.

• style_operator_arithmetic
• style_operator_boolean
• style_operator_integer

These existing rules are for the number of following spaces and do not support leading spaces.

For example:

When I give the following SystemVerilog code to the linter with style_operator_arithmetic rule enabled,

module M;
  localparam int P2 = a  + b; // Multiple spaces before `+`.

  // No space before `*`.
  localparam int P3 = a* b;

endmodule

I expect the result that says the numbers of the leading spaces of * and + operators are not appropriate, but no message will be found actually because this existing rule do not consider leading space.

With the new rules I implemeted, this message will be found for the sample code.

Fail: style_operator_arithmetic_leading_space
   --> test.sv:2:26
  |
2 |   localparam int P2 = a  + b; // Multiple spaces before `+`.
  |                          ^ hint  : Put exact one space before binary arithmetic operators.
  |                            reason: Consistent use of whitespace enhances readability by reducing visual noise.

Fail: style_operator_arithmetic_leading_space
   --> test.sv:5:24
  |
5 |   localparam int P3 = a* b;
  |                        ^ hint  : Put exact one space before binary arithmetic operators.
  |                          reason: Consistent use of whitespace enhances readability by reducing visual noise.

The new rules only consider the number of leading spaces. (do not consider following spaces)

[DaveMcEwan]

@so298 Nice one :) I notice a couple of little things.

1. Can you add your name to the list of contributors (bottom of CONTRIBUTING.md) as part of this PR.
2. Should these be enabled in the style ruleset? These new rules look like a great addition to me :)
3. Minor spelling change in the hints, "exact" -> "exactly".

[so298]

@DaveMcEwan

Thank you for your comment!

I agree with the idea that these rules are enabled in the style ruleset.
I modified rulesets/style.toml in the last commit.

Also, I fixed spelling mistake and added my name to CONTRIBUTING.md.

[so298]

@DaveMcEwan
Merged so298#1
Sorry for being late.

[dalance]

Thank you for your contribution.
I'll merge this PR.